Turbochargers have been developed to increase the power output to weight ratio of engines. Thus, the power output of an engine may be increased without a substantial increase in an engine's weight or an engine's size (e.g., displacement). Alternatively, engine displacement may be decreased while the engine provides an equivalent amount of output power as a larger non-boosted engine.
However, turbochargers may experience turbo-lag. Turbo-lag may be defined as the time needed to change the speed of the turbocharger to produce a desired amount of boost in response to a change in engine torque demand. Turbo-lag may provide less than desirable engine performance.
Twin-turbocharger systems have been developed to reduce turbo-lag. Specifically, a turbocharger is provided for each of two cylinder banks. Efficiency of each of the two turbochargers may be adjusted via wastegates. Each wastegate regulates flow through a passage that begins upstream of one of the turbocharger turbines and returns exhaust gas to a location downstream of the same turbocharger turbine in an exhaust passage that directs exhaust away from only the cylinder bank sending exhaust to the turbocharger turbine. Thus, each bypass passage bypasses one of the turbines and not the other turbine.
However, the Inventors have recognized several drawbacks with utilizing a wastegate for each turbine in an engine having a parallel turbocharger configuration. For example, it may be costly to employ two wastegates in an engine. Furthermore, the profile of the exhaust system may be increased when two separate wastegates are utilized. Also, it may be desirable to have balanced exhaust flow traveling through each of the turbines and/or bypass conduits in a parallel turbine arrangement. However, due to manufacturing, control, and design differences between the two turbines, the wastegates may not provide an equivalent exhaust gas bypass around each of the turbines. Such conditions may lead to unbalanced exhaust flow and torque differences between cylinder banks. As a result, the turbocharger operation may be degraded.
As such, in one approach a turbocharger system is provided that may improve flow equalization between cylinder banks. The turbocharger system includes a first turbocharger including a first turbine in fluidic communication with a first cylinder, a second turbocharger including a second turbine in fluidic communication with a second cylinder, and a shared bypass conduit having a sole wastegate coupled thereto, the shared bypass conduit in fluidic communication with a first turbine inlet and a second turbine inlet. In this way, a single bypass conduit and wastegate may be used to bypass two turbines. As a result, the possibility of imbalanced bypass operation may be reduced. Moreover, the cost as well as size of the turbocharger system may be reduced when compared to turbocharger systems employing two wastegates and bypass conduits.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.